Polycrystalline is also about 20% cheaper to produce and creates less waste silicon in the process. If you’re looking for the lowest price, polycrystalline panels are probably your best bet. However, polycrystalline experiences internal efficiency losses due to the structuralinconsistency at the seams where two different crystals meet; due to the lower purity of the silicon. Polycrystalline panels have about 13 to 16% efficiency, while monocrystalline panels have an efficiency rate of anywhere from 15 to 20%. You would need a much larger array of polycrystalline panels to produce the same amount of energy than if you used monocrystalline, which may not work for households with limited roof space.